Possible link between low vitamin D and pain in women
Publication Date:14/08/2008
Researchers have found evidence of a link between low vitamin D levels and chronic pain in women. But the link is far from definite and we don’t know whether taking vitamin D supplements would be any help for women with long-term pain.
What do we know already?
Vitamin D is made in your skin, after you've been in the sun. You can also get vitamin D in some foods, including eggs and oily fish, although most people get the vitamin D they need from sunshine.
Vitamin D is important because it helps your body absorb calcium, to make healthy bones. Previous studies have shown that people with a bone disease called osteomalacia, who often have bone pain, have very low vitamin D levels. But researchers don’t know if vitamin D makes a difference to pain in people without this bone disease.
The new study looked at 9,377 people aged about 45, who are taking part in a long-term health study. The researchers measured their vitamin D levels, then asked them to fill in a questionnaire about their health, including whether they had long-term pain that was widespread across their body.
What does the new study say?
There was no link between vitamin D levels and the likelihood of having long-term widespread pain in men. There was a possible but not definite link between vitamin D levels and pain in women. However, other things like women’s social class, and lifestyle factors like whether they smoked, made more of a difference to whether they got long-term pain than vitamin D.
Tell me more about the study’s findings
The women least likely to have long-term widespread pain had vitamin D levels of 75 to 99 nmol/l (short for nanomoles per litre, a measurement for very small amounts of a substance in liquid).
The study found that 8 in 100 women with vitamin D levels in this range had pain. Between 12 in 100 and 15 in 100 women with lower levels of vitamin D had pain.
Much, but not all, of the difference in pain at different vitamin D levels disappeared when researchers took into account other things like whether the women smoked, and what social class they were in. There was no link between having pain and whether or not women took vitamin D supplements.
Where does the study come from?
The study was carried out by researchers from University College London and the University of Aberdeen. It was published in the Annals of the Rheumatic Diseases, a medical journal owned by the British Medical Association.
How reliable are the findings?
The researchers themselves say that their findings give ‘little support’ for the idea that vitamin D levels cause long-term widespread pain. They say they cannot rule out the possibility that women with long-term pain had low vitamin D levels because they had changed their behaviour due to the pain, rather than the other way round. For example, women with pain might be less likely to spend time out of doors, so they’d get less sunlight than women without pain.
It's odd that there was a link for women, but not for men. The researchers say this could have been because women react differently to vitamin D, because of their hormones. But equally, it could be that women were more likely to stay inside when they had pain, compared to men with pain.
What does this mean for me?
Experts say that most people can get the vitamin D they need from sunlight and food. The study does not suggest that taking vitamin D supplements can help if you have long-term pain. The researchers say that different studies are needed to find this out.
If you have long-term pain, this study suggests that other things about your lifestyle may be more important than whether you have enough vitamin D. But we can’t rule out that vitamin D may have some effect for women.
The government recommends that pregnant women, and elderly people, take a 10 mcg (micrograms) supplement of vitamin D. That’s because you may need more vitamin D in pregnancy, and older people are less likely to get enough vitamin D from sunshine. We don’t know if this is helpful for other people.
Most of the people in the study (98 in 100) were white. There’s some evidence that people with dark skins living in countries like the UK, which get less sunshine, are more likely to have low levels of vitamin D. We don’t know if the results would be different for black and Asian people in the UK.
What should I do now?
There’s no need to take any action as a result of this study.
From:
Atherton K, Berry DJ, Parsons T, et al. Vitamin D and chronic widespread pain in a white middle-aged British population: evidence from a cross-sectional population survey. Annals of the Rheumatic Diseases. August 2008. Available at http://ard.bmj.com/cgi/content/abstract/ard.2008.090456v1 (accessed on 14 August 2008).
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